The invention relates generally to intake and exhaust systems for internal combustion engines of the type conventionally used in motor vehicles. More specifically, the invention relates to intake and exhaust system components and accessories used to provide improved fuel economy and performance. The invention also more specifically relates to such components and accessories which provide enhanced combustion efficiency by improving mixing of the air and fuel entering the engine or by improving exhaust gas flow through the exhaust system.
In a conventional internal combustion engine's intake system, the fluid flow which moves adjacent the walls of the intake passageway i.e., laminar fluid flow, typically includes a substantial amount of gasoline that is not atomized. Fuel that is not atomized does not readily combust. Thus, incomplete atomization of the fuel in the fluid flow hinders complete combustion of the fluid. This laminar flow consequently reduces the combustion efficiency of the engine. In addition, due to the frictional forces generated by contact of the fluid flow against the walls of the intake passageway, the laminar fluid flow travels through the passageway at a slower velocity than the rest of the fluid flow. Moreover, due to the difference in mass density between the gasoline molecules and the air molecules in the laminar fluid flow, the gasoline molecules experience greater frictional forces via contact with the walls of the passageway than the air molecules resulting in slower moving gasoline molecules than air molecules. This difference in velocity tends to additionally hamper mixing of the gasoline particles with the air particles thereby further contributing to incomplete combustion of the fluid and reducing the efficiency of the engine in converting heat energy to mechanical energy.
Inducing turbulence in the fluid flow passing through the intake passageway reduces laminar fluid flow and moves the slower moving gasoline particles away from the walls of the passageway thereby preventing further deceleration caused by contact with the walls. Both of these effects result in improved mixing of the air and fuel. Such benefits can be realized if turbulence is induced either in the air entering the carburetor (or fuel injection system), in the fluid passing through the intake manifold or intake runners or in the fluid passing through the intake ports or around the intake valves of the engine. Consequently, various devices and systems have been designed to induce such turbulence at various locations in the intake system.
Some prior art devices which are designed to produce turbulence in the air entering the fuel introduction subsystem include vanes which deflect the air passing thereagainst in order to impart a swirling motion to the air. Some such devices include a hub or central member to which the device vanes are attached. The central member provides rigidity to the vanes so that they do not absorb energy of deflection but rather transmit that energy back to the fluid. The central member is typically streamlined in order to reduce obstruction of fluid flow and reduce negative pressure areas which would otherwise create undesired turbulence. Nevertheless, the central member requires a certain degree of structural strength to hold the vanes steady while withstanding the forces of the fast moving fluid flow. In addition, the central member must be a certain relatively large size in order to enable the vanes to be securely and rigidly connected thereto. Due to these requirements, the central member is typically large and thus significantly reduces the cross-sectional area of the intake passageway thereby reducing fluid flow therethrough. The central member also acts to block the air flow at the central area of the intake passageway. Since the highest velocity of fluid flow is in the central area, the highest mass of fluid moving through the passageway is also in the central area. Thus, a blockage in this area is more likely to affect the amount of fluid flow in the passageway than a blockage in another area. Consequently, such central members typically reduce fluid flow through the intake system and thereby reduce the power output of the engine.
Others of such prior art device which induce turbulence through the use of vanes do not utilize a central member in order to eliminate the likelihood that such members would present a significant obstruction to air flow. Such of these devices utilize vanes which are radially curved to attach both ends of the vanes to the same side of the cylindrical housing. However, the vane portions which are at the central area produce higher stresses at the attachment points due to the effects of leverage. In addition, the absence of a secure central connection and thereby lack of rigidity of the vanes at the central area results in deflection movement in response to the forces of the fluid flow. The movement of the vanes may adversely affect the fluid flow movement by setting up harmonics in the fluid, by absorbing energy from the fluid flow or by undesired deflection of the fluid flow. The vanes are often made thicker in an attempt to obviate these shortcomings. However, the thicker vanes reduce the cross-sectional area of the passageway thereby tending to reduce fluid flow through the passageway.
Many of the prior art devices that induce air turbulence are manufactured in various sizes to accommodate the differently sized and structured intake systems of the many makes and models of motor vehicles on the market. Some of these prior art devices are simply dimensioned adequately fit in the duct in which placed while others are designed to be diametrically resilient to exert a force against the inner walls of the intake duct and thereby provide a more snug fit therein. This prevents displacement of the device within the duct and also allows it to accommodate small variations in the diametrical sizes of these ducts. However, due to the oftentimes high vibrations acting on the device while in use and during vehicle operation this snug fit is often not enough to prevent displacement of the device. Displacement of the device from its intended position can result in damage to the device, the duct or other parts of the intake system or engine. As a result of these problems many of these devices are instead designed to fit in other parts of the intake system in which component structures thereof are available to secure the device therein.
One of the primary disadvantages of prior art devices or systems that generate intake air turbulence is that the structures thereof that produce the desired turbulence also restrict air flow through the system. This undesirably reduces the maximum quantity of air and fuel that is delivered into the engine thereby reducing its maximum horsepower output. An example of a prior art device that generates swirling and also turbulence of the intake air is disclosed in U.S. Pat. No. 5,947,081 to Kim. The device disclosed includes vanes which have slits as well as concave and convex portions. The small concave and convex surface portions of the vanes deflect small portions of the air flow at relatively sharp angles of deflection. The high degree of deflection produces turbulence of the air stream. This turbulence includes collision of fluid flow molecules rather than a smooth blending or mixing of the fluid flow. Consequently, the collisions absorb energy thereby reducing the velocity of the fluid flow and consequently reducing fluid flow.
Another important disadvantage of some prior art devices is that they are difficult or expensive to mount in the engine system. Some prior art devices such as that disclosed in U.S. Pat. No. 4,424,777 to Klomp require that they be installed around the intake valves necessitating that the purchaser disassemble the engine and have engine components suitably machined to adapt these components to the device. But, this is typically a time consuming and expensive endeavor rendering such devices impractical for many motor vehicle owners. Similarly, other prior art devices require that they be installed in the intake manifold or runner necessitating that the purchaser disassemble major components of the engine in order to install such devices. But, this is also a time consuming and expensive endeavor requiring a degree of mechanical skill rendering such devices impractical for many motor vehicle owners.
Designers of such prior art intake fluid turbulence generation systems have recognized that the effectiveness of such turbulence varies according to the engine throttle position. U.S. Pat. No. 4,424,598 to Tsutsumi discloses an automobile swirl producing system which is responsive to engine load and engine operating conditions. Basically, the Tsutsumi system uses a pivot shaft responsive to carburetor throttle valve position to alter the swirl produced in the combustion chamber. However, the disadvantage of such a system is that it is difficult to properly install, and this especially discourages many do-it-yourselfers from purchasing it.
Designers of exhaust systems have also recognized that improving the rate of exhaust gas flow out of the engine can provide improved combustion efficiency. There have consequently been many exhaust systems that have sought to increase the velocity of exhaust gas flow out of the exhaust system and thereby in effect scavenge exhaust gases from the combustion chamber and exhaust ports. Some exhaust header systems have been designed to position exhaust pipes around the inner circumference of a collector pipe to produce swirling of the exhaust gases from the collector pipe in a vortex flow and thereby enhance exhaust gas flow therefrom. Such systems have been very effective in improving exhaust as well as intake fluid flow and thereby improving combustion. However, such systems require retuning of the carburetor or fuel injection system and ignition system of the engine as well as replacement of major engine system components and are thus impractical for many motor vehicle owners. In addition, such systems typically do not meet government emission standards requirements and are thus undesirable for the typical vehicle owner.
The many requirements for such air swirling or air turbulence generating devices and systems have resulted in prior art systems and devices in which there are compromises between swirl or turbulence generation and air flow restriction. In addition, there have also been many prior art systems that have been very effective in generating the required swirl or turbulence yet have necessitated undue engine component alterations and labor consumption. Consequently, what is needed is an intake and exhaust fluid swirling device which does not require special tools for installation and thus may be easily manually installed. What is also needed is an intake and exhaust fluid swirling device providing enhanced swirl generation while producing minimal fluid flow restriction. What is additionally needed is such a device which may be securely positioned in passageways of intake and exhaust systems.